Live generally gets it right at this point. You can turn on the metronome to hear that the track is warped correctly throughout.

Next, turn on the clip's Loop button:

Set the Length to 4 Measures:

Set the position to 1.1.1.

Now we hear a four-bar loop. (You can click on the word "Length" to zoom in to that loop.) You can click and drag in the tempo field to change the tempo of your loop.

You may want to play with the warp modes for better sound. Complex or Complex Pro are best for mixed-down songs. Use Beats for drums, and Tones for instruments like guitar, vocals, piano, and so on.

To check the rest of the track and make sure that it is correctly warped, click on the loop bracket, and use the arrow up and arrow down keys to move through the rest of the song. Add, adjust or get rid of Warp Markers as necessary.